Pushbutton piezoelectric igniter



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AKIO SUZUKI n y//l il jK ATTORNEY June 10, 1969 Amo suzuKl PUSHBUTTONPIEZOELECTRIC IGNITER Filed Dec. 29, 1967 Sheet I K1 O ON m. @E E mmINVENTOR. AKIO SUZUKI AT TOR NE'Y United States Patent U.S. Cl. 317-8110 Claims ABSTRACT OF THE DISCLOSURE A pushbutton piezoelectric igniterfor manual actuation having an elongated tubular housing carrying apiezoelectric element which is actuated by impact. 'Ihe impact mechanismis also generally tubular and includes a push rod carrying a springbiased hammer, a latch for restraining the hammer while the push rod isbeing depressed until the rod lifts off the restraining force andpermits the hammer to suddenly strike the piezoelectric element. Amodification includes a stationary outer sleeve telescoped over thehousing so that the main body but particularly the electrode may beshifted into and retracted from the flame area.

This invention relates generally to piezoelectric igniters and moreparticularly to piezoelectric igniters of the type having a mechanism inwhich the piezoelectric element is actuated by means of a sudden hammerblow.

In the prior art piezoelectric igniters, as categorized in the precedingparagraph, are already known. Most of these devices are neither compactnor generally suitable for use in household gas appliances or the like.This type of application requires utmost simplicity of operation. It hasalso been `found that at times the tip of the electrodes forming thespark gap are exposed continuously to the flame area of the device inwhich the igniter is employed Iand the exposure to excessive heat causesdeterioration of the electrode.

It is therefor-e the primary object of this invention to` provide atubular, pushbutton type piezoelectric igniter of utmost simplicity.

It is `a further object of this invention to provide a piezoelectricigniter .of the type described in the preceding paragraph in which theelectrode or electrodes lforming part of the igniter can be moved intoth-e area proximate to the source of gas which is to` be ignited and canbe retracted after ignition.

An aspect of the present invention resides in the provision o-f 'apushbutton piezoelectric igniter 'which includes a longitudinallyextending housing and a piezoelectric element which is c'arried in thehousing and is responsive to pressure in the longitudinal mode togenerate a voltage. The housing also contains a striking mechanism whichis normally spaced relative to the piezoelectric element and is adaptedto impart a sudden hammer blow upon the latter. 'Ihe striking mechanismis housed within la tubular push rod coaxially disposed within thehousing. A spring arranged between the striking mechanism and therelative end of the tubular rod is effective for biasing the strikingmechanism toward the piezoelectric element. A latch initially restrainsthe movement of the striking mechanism while the tubular push rod ismoved against the bias of the spring toward the piezoelectric elementuntil the tubular r-od causes the restraining force of the latch to belifted and the striking mechanism to be free to impart a hammer blow tothe piezoelectric element to generate a voltage.

Another -aspect of the present invention resides in the provision of apiezoelectric igniter of the type described 3,449,637 Patented June 10,1969 ICC in the preceding paragraph in which, however, la tubular sleeveis telescoped over the housing for relative axial movement therewith.and is adapted to carry one end of the latch so that the electrodeextending centrally from the forward end of the element thnough the tipof the housing may be moved into and retracted from the ignition area.

For a better understanding of the present invention, together with otherand further objects thereof, reference is had to the yfollowingdescription taken in connection with the accompanying drawings, and itsscope will rbe pointed out in the appended claims.

In the drawings:

FIGURE 1 is an axial view, showing partly in cross section, of thedevice in accordance With this invention;

FIGURE 2 is a view similar to FIGURIE 1, illustrating the igniter withthe push button actuator partly depressed;

FIGURE 3 is a view similar to FIGURE l, illustrating the igniter withthe push button completely compressed and just after the release of thelhammer;

FIGURES 4 to 6 are views similar to FIGURE l, illustrating in the samesequence as FIGURES l to 3, respectively, a modification of the presentinvention.

Referring now to the drawings and, more particularly, to FIGURES l to 3thereof, there is shown a tubular, longitudinally extending housing A10,composed of plastic insulating material such as polytetrlafluoroethyleneor the like. The tubular housing comprises at the forward end thereof acap having a |female thread to receive a rearwardly extending body 14 ofthe housing 10 which threadedly protrudes into the end cap 12. The endcap 12 is provided with .an axial extension 15 to carry and support thehot lead 16. The hot lead or electrode 16 is an elongated wire whichextends substantially beyond the terminal end of the axial extension 15and may be formed in a number lof ways, in the preferred embodiment the`fonward end thereof has fa pointed end and the rear portion has anintegral radial flange 18 which labuts against a shoulder 21 formed inthe end cap 12` to prevent the axial or lateral movement of theelectrode 16.

A piezoelectric element 20 of cylindrical configuration and composed ofa poly-crystalline ceramic material such as barium titanite, leadtitanite zirconate or the like is suitably polarized and electroded torespond to a compressive force in the longitudinal mode and the endopposite to the hot lead flange 18 or disc is grounded by means of ametal end disc 22. The predominant portion of the ceramic element 2.0 isembedded in the tubular body 14 while a forward end portion projectsinto the end cap I12.. The disc 22 abuts a shoulder 24 lof the housing14 to prevent axial displacement of the piezoelectric element 20. Theelement 20 is loaded into the housing body 14 by removing the end cap 12and by loading. the body 14 with the disc 22, the element 20 and theelectrode 16, all olf these members being suitably in axial alignment.

The housing body 14 is formed with Ia slot 26 extending lengthwiseparallel v to the longitudinal device and in depths extending radiallycompletely through the housing body 14 to accommodate a component of theactuating mechanism 34 which is hereafter further described.

The actuating mechanism 34 comprises a tubular rod 36 which in part ismovably disposed within the tubular housing body 14, in coaxial fashion,`and in a manner permitting reciprocatory movement. The tubular rod 36or, as hereafter also referred to as push rod, slidably carries withinthe forward end thereof a hammer 38 of cylindrical configuration adaptedfor axial movement within the push rod. This movement is limited by adetent 40 extending transversely through the cylindrical body of thehammer 38. The hammer detent 40 traverses within the confines of narrow,longitudinally extending slots 42 formed 180 degrees apart in push rod36. The location of slots 42 and detent 40 and the geometricconfiguration of the hammer 3-8 are to permit the hammer 38 in its mostforward position, as shown in FIGURE 1, to project axially beyond thepush rod 36 in order to permit a hammer blow contact with metal strikerpin 28 which is disposed in the tubular body 14 in bearing relation tothe piezoelectric element 20 by abutting the ground disc 22.

The rear end of push rod 36 is provided with an integral end wall 44 anda helical compression spring 46 is interposed between the wall 44 andthe hammer 38 in order to bias the hammer at all times in the forwarddirection. A pushbutton 48 is telescoped over the wall 44 withcylindrical wall portions thereof in radially spaced relation to thehousing body 14 in order to form a space 50 therebetween. The tubularhousing body 14 has a recessed diameter at the rear end so that acompression spring 52 can be placed helically around the push rod 36 andbetween the push button 48 and the shoulder 54 which results from therecess mentioned above. The function of the spring 52 is to bias thepush rod 36 rearwardly at all times. A detent r516 in the form of aradially extending screw projecting into the slot `42 to limit theoutward movement of the push rod 36 and to prevent an accidentalejection thereof.

With the springs 46 and 52 in place, the push rod 36 carrying hammer 38assumes the position as shown in FIGURE 1, a latch 58 normally grips thedetent 40` to restrain the movement of the hammer. The latch 58 isprovided with a cutout which is generally complementary to theconfiguration of detent 40 and the rear end thereof has an inclinedsurface 60, substantially matching the slanted surface 62 of the walldefining the rearward limits of the slot 42 of the push rod body 36. Inthe preferred embodiment, the latch 58 is provided at the forward endwith a transversely extending pin 64 which rests in a transverse cutout66 in the circumference of the `housing body 14; the latch `58 thusbeing rotatably anchored at one end by means of pin 64. The latch isfree to move within slot 26 radially about the axis of pin `64. Thisradial movement is limited by means of a leaf-type spring `68 solderedat one end to the latch 58 and bearing against an outer tubular metalsleeve 30" which is part of the housing. The spring 68 is effective tobias the latch toward the hammer 38 and, more particularly, the detent40.

The tubular metal sleeve 30 which is placed over the housing body 14,thereby covering the slot 26, securely receives one end of the groundelectrode 70 the other end of which terminates proximate to the axialend of electrode 16 to establish an ignition spark gap therebetween.

In operation when the device is in a condition as shown in FIGURE l, thepush button 48 is pressed in relation to the housing body 14 therebycompressing, as shown in FIGURE 2, the spring 46 arranged between endwall 44 and the hammer 38 as well as the spring 52 disposed between thepushbutton 48 and the housing body 14. In this first stage of theoperation, the latch 58 causes the hammer 38 to stay stationary relativeto the housing body 14 while the push rod 36 moves relative thereto. Inother words, the slots 42 in the push rod 36 permit the hammer 38 to bemaintained in the position noted above.

FIGURE 2 illustrates a condition just prior to the liftotf of latch 58due to the bearing contact of the slanted surface 62 of push rod 36 withthe inclined surface 60 of the latch 58.

Additional forward movement of the push rod 36 causes the latter torelease the restraining force of the latch S8 upon the detent 40 therebyreleasing the potential energy of the spring 46 causing the hammer 38 tomove against and impart a blow to the striker pin 28 which in turncauses the piezoelectric element to be cornpressed and to generate avoltage which is transmitted through the electrode 16 thereby causingthe gap 72 to be ionized and the gas or the combustible material to beignited. The release of the actuating force, which in most instanceswill be manual, causes the spring 52 to return the push rod 36 to itsoriginal position, at which point the device is in a position again forthe next ignition cycle.

While the so-called hot lead of the electric circuit is composed ofelectrode 16, 18, the ground connection is circuitous and at the momentof impact and voltage transmission leads through the metal end disc 22,striker pin 28, hammer 38, detent 40, latch 58, leaf-type spring 68,tubular sleeve 30 and ground electrode 70.

The FIGURES 4 to y6 illustrate a modification of the device described inthe preceding paragraphs and like reference characters are utilized todesignate like or similar parts of the modified device except that aprime mark has been utilized for distinguishing purposes.

In the modified device, no relative axial movement takes place betweenthe push rod 36' and the tubular housing member l10. The end cap 12 hasbeen deleted and the piezoelectric element 20 and associated parts areloaded into the tubular body from the rearward end of the housing.Thereafter the actuating mechanism 34 together with associated parts,such as the hammer 38', are inserted from the back into the tubularhousing 10'. The restraining latch 58' works in the same manner asbefore discussed except that this member is carried by'a circular sleeveconsisting of an outer metal tube 81 and an inner tube 83. The sleeve istelescoped over the housing body 10 and with a radial projection 88extending from the inner tube 83 into and movable within a longitudinalslot 82 in the housing body 10. A compression spring 84 is interposedbetween the pushbutton 48 and the sleeve `80 in order to retract theactuating mechanism 34.

In the operation of the device shown in FIGURES 4 to 6 the sleeve, inthe preferred manner of carrying out this invention, is held stationaryand the pushbutton 48' is depressed in the direction of the sleevecausing the tubular housing 10 and the push rod 36 and, of course, theelectrode 16', to be axially displaced relative to the sleeve 80 therebycompressing springs 46' and 84.

The dotted line in FIGURE 4 outlines the extent to which the electrode.16 is projected into (the high tem perature ame area) and retractedfrom the area ignition takes place. An ignition -gap is not shown butmay be arranged as illustrated in FIGURE 1.

FIGURES shows the device just prior to contact between the inclinedsurfaces 60 of the latch 58 and 62 of the push rod 36'. In FIGURE 6, afurther depression of the pushbutton 48 has caused the latch 58 to belifted off the detent 40 and the latch 58 now rests in the vicinityabove the slanted surface 62'. The spring 46', after the restrainingforce of the latch 58' has been removed, causes the hammer 38' tosuddenly strike the striker pin 28. In this embodiment, a spring 86 isinterposed between the hammer 38 and the striker pin 28 so that thecompressive force is transmitted first through the spring 86 and onlythen through the striker pin 28. The spring 86 is anchored with aninterference fit in the tubular housing 10 to prestress thepiezoelectric element 20 as desired.

The invention described above is particularly suitable as an igniter ingas appliances, gas lighters such as cigarette lighters, torches or thelike. It is also obvious that the pushbutton may be modified to fit theparticular application without deviating from the basic concept of thisinvention.

While there have been described what are at present considered to be thepreferred embodiments of this invention, it will be obvious to thoseskilled in the art that various changes and modifications may be made -5therein without departing from the invention, and it is aimed,therefore, in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A pushbutton piezoelectric igniter comprising, in combination:

a longitudinally extending tubular housing;

piezoelectric element means disposed within said housing in electricalnon-conducting contact with the latter and responsive to pressure in thelongitudinal mode to generate a voltage;

striking means spaced relative to said element means and adapted toimpart a hammer blow upon the latter;

a tubular member coaxially within said housing; said striking meansbeing movably carried within said tubular member at the forward endportion thereof;

spring means between said striking means and the rear end of saidtubular member for biasing said striking means toward said piezoelectricelement means; latch means adapted for restraining the movement of saidstriking means;

a pair of electrode means, one end of each electrode means electricallyconnected to said piezoelectric element means and the other end of eachelectrode means forming a spark gap;

and manually actuated means on said tubular member for moving the latteragainst the bias of said spring means toward said element means whilesaid latch means holds said striking means stationary until said tubularmember releases the restraining force of said latch means causing saidstriking means to impart a hammer blow to said piezoelectric means togenerate a voltage and to spark across said gap.

2. A pushbutton piezoelectric igniter according to claim 1, and one ofsaid electrode means extending centrally from the forward end of theelement means coaxially through the tip of the housing.

3. A pushbutton piezoelectric igniter according to claim 1, and anactuating pushbutton on the rear end of said tubular member.

4. A pushbutton piezoelectric igniter according to claim 3, and ahelical compression spring coaxially sur- 6 rounding said tubular memberand being interposed between said pushbutton and said housing to returns aid tubular member to its normal rearward position.

5. A pushbutton piezoelectric igniter according to claim 4, and a detentmember within said tubular member and abutting said striking meansadapted for causing said striking means to be returned rearwardlytogether with said tubular member.

6. A pushbutton piezoelectric igniter according to claim 1, a tubularsleeve telescoped over said housing for relative axial movement with thelatter and adapted to carry one end of said latch means.

7. A pushbutton piezoelectric igniter according to claim 6, wherein saidtubular member and said housing are caused to be moved relative to saidtubular sleeve in response to actuation of said actuated means.

8. A pushbutton piezoelectric igniter according to claim 7, one of saidelectrode means extending centrallyfrom the forward end of the elementmeans coaxially through the tip of the housing, whereby upon actuationof said actuated means said electrode is axially displaced relative tosaid sleeve.

9. A pushbutton piezoelectric igniter according to claim 6, and anactuating pushbutton telescoped over the common rear end of said tubularmember and the housing.

10. A pushbutton piezoelectric igniter according to claim 9, and aspring interposed between said pushbutton and said sleeve.

References Cited UNITED STATES PATENTS 3,271,624 9/ 1966 Kingma et al.317-81 3,298,421 1/ 1967 Tezuka et al. 317-81 X 3,387,912 6/1968 Goto317-81 X 3,408,153 10/ 1968 Ishigoto 431-143 FOREIGN PATENTS 606,498 10/1960 Canada.

VOLODYMYR Y. MAYEWSKY, Primary Examiner.

U.S. Cl. X.R. 310-8.7; 317-96

